Stereotactic Body Radiation Therapy for Prostate Cancer: Review of Experience of a Multicenter Phase I/II Dose-Escalation Study
Stereotactic Body Radiation Therapy for Prostate Cancer: Review of Experience of a Multicenter Phase I/II Dose-Escalation Study
复制标题
前列腺癌立体定向全身放射治疗：多中心 I/II 期剂量递增研究经验回顾
作者：
D. Kim;C. Straka;L. Chinsoo Cho;R. Timmerman;A. Katz;James Byunghoon;Yu
简介：立体定向体部放射治疗（SBRT）是治疗前列腺癌的一个积极研究领域。在我们的I期剂量递增研究中，未达到最大耐受剂量（MTD），随后完成了II期研究。本文的目的是回顾我们的经验，剂量递增SBRT局限性前列腺癌。方法和材料：回顾2006年至2011年入组I/II期研究的患者。处方剂量组为45、47.5和50戈瑞（戈伊），分5次给药，持续2.5周。收集并分析毒性和生活质量问卷数据。以连续变量的平均值、中位数和范围以及分类变量的频率和百分比的形式获得描述性统计量。结果：从5家机构入组了91例患者。前列腺特异性抗原（PSA）评估的中位随访时间为42个月。PSA控制在99%。虽然在I期研究中未达到MTD，但在II期研究中观察到过度高度直肠毒性（10.6%）。在I期研究中接受50戈伊治疗的13名患者没有高度直肠毒性，回顾起来符合这些参数，并且在较长的随访中没有进一步的事件。结论：在这些剂量水平下，前列腺特异性抗原的控制率，即使对于中度风险的患者，也是极好的。本研究为探索基于SBRT的临床试验提供了一个平台，旨在优化中高危患者的结局。在最高剂量水平下，在少数但有意义的少数患者中观察到与直肠特异性相关的高度毒性。已经定义了基于生理参数的剂量限制，以减轻这种风险，并且正在探索最大限度地减少直肠暴露于这种剂量的策略。
Introduction: Stereotactic body radiation therapy (SBRT) is an area of active investigation for treatment of prostate cancer. In our phase I dose-escalation study, maximum-tolerated dose (MTD) was not reached, and subsequently phase II study has been completed. The purpose of this article is to review our experiences of dose-escalated SBRT for localized prostate cancer. Methods and materials: Patients enrolled to phase I/II study from 2006 to 2011 were reviewed. Prescription dose groups were 45, 47.5, and 50 Gray (Gy) in five fractions over 2.5 weeks. Toxicity and quality of life questionnaire data were collected and analyzed. Descriptive statistics were obtained in the form of means, medians, and ranges for the continuous variables, and frequencies and percentages for the categoric variables. Results: Ninety-one patients were enrolled from five institutions. Median follow-up for prostate specific antigen (PSA) evaluation was 42 months. PSA control remains at 99%. While the MTD was not reached in the phase I study, excess high grade rectal toxicity (10.6%) was noted in the phase II study. The 13 patients treated to 50 Gy in the phase I study that did not have high grade rectal toxicity, in retrospect met these parameters and have not had further events on longer follow-up. Conclusion: Prostate specific antigen control rate, even for patients with intermediate risk, is thus far excellent at these dose levels. This study provides a platform for exploration of SBRT based clinical trials aimed at optimizing outcome for intermediate and high risk patients. High grade toxicities specifically related to the rectum were observed in a small but meaningful minority at the highest dose level. Dose constraints based on physiologic parameters have been defined to mitigate this risk, and strategies to minimize rectal exposure to such doses are being explored.